1. Field of the Invention
The present invention relates to a method of manufacturing an oxide superconducting wire by plastically working an oxide superconductor into a wire, and more particularly, it relates to an improvement in a plastic working step.
2. Description of the Background Art
In general, an oxide superconducting wire is manufactured by filling up a metal pipe with oxide raw material powder, working the same into a wire through a step of plastic working such as extrusion, wire drawing, rolling or the like, and thereafter heat treating the wire. It is known that such plastic working and heat treatment are effectively repeated in order to improve critical current density of the as-formed wire.
In relation to such a method of manufacturing an oxide superconducting wire, densification of the oxide superconductor filling up the metal pipe contributes to improvement of critical current density. In order to densify the oxide superconductor, therefore, it has been necessary to perform flat working on the basis of press working, roll working or the like. The flat working is adapted to compress a round wire, for example, along its sectional direction, thereby working the same into a wire having a flat section. Such flat working is generally carried out in a plurality of stages in order to reasonably attain a desired sectional configuration or desired dimensions. Thus, flat working based on press working is inferior in high-volume production capability since it is necessary to perform flat working in sequence on every portion of a wire, while that based on roll working is inferior in workability since a plurality of working steps are carried out.